Phonograph record resurfacing tool



Nov. 22, 1938. w, 2,137,621

PHONOGRAPH RECORD RESURFACING TOOL Filed Sept. 18, 1957 INVENTQR (Mal-tar 7K 977iller BY 84. a-Lo-u,

, TTORNEY Patented Nov. 22, 1938 UNITED STATES PATENT OFFICE Walter H. Miller, South Orange, N. J., assignor to Thomas A.

Edison, Incorporated, West Orange, N. J., a corporation of New Jersey Application September 18, 1937, Serial No. 164,477

Claims.

The present invention relates to machines for shaving cylindrical phonograph records and more particularly to improved means for obtaining a smooth record surface in the shaving process. The invention is especially concerned with the shape of the cutting edge of the resurfacing tool and the relative position which this tool bears to a record during the operation of shaving the latter.

Cylindrical records made of wax-like material are commonly employed in commercial phonographs, or dictating machines. In using a dictat-ing machine there is made upon such a record a recordation which comprises a groove cut progressively into the record body material at a depth, or with a sidewise movement, undulating in accordance with the sound waves. These recordations are seldom meant to be preserved permanently, but are rather intended to be transscribed from after which the record is prepared for reuse.

Inasmuch as the depth of the recorded groove is small and the wall thickness of the cylindrical phonograph record is relatively great, the record may be resurfaced after each recording and transcribing operation in order to be used again. The resurfacing operation involves the cutting away of a layer, or layers, of the record material of an over-all thickness that is at least equivalent to the maximiun groove depth. It is very desirable that this resurfacing be done in a man ner to obtain a surface of a high degree of smoothness, as this is important in obtaining a minimum level of record surface noise. My invention is principally concerned with a novel form of shaving knife-for securing improved results in shaving cylindrical phonograph records, as is here described.

It is an object of my invention to obtain through improved shaving means a smoother record surface than has heretofore been obtained in the field of the art.

It is another object to obtain an improvement in smoothness of resurfaced cylindrical phonograph records without deviating materially from long established and practical shaving procedure.

It is another object to obtain a resurfacing of cylindrical phonograph records of present acceptable smoothness at a higher rate of speed.

It is another object to employ a resurfacing tool having a concavely shaped cutting edge for cutting on a cylindrical phonograph record a wide groove in a manner that facilitates the removal of the shaving chips.

It is still another object to employ a knife blade having a concavely shaped edge in such a manner that it cuts a wide groove of small curvature on a cylindrically shaped record.

Other objects of my invention will be apparent from the following description and claims. 5

In order that my invention may be more clearly understood, attention is directed to the drawing accompanying and forming a part of this specification, and in which:

Figure 1 is a sectional view, partly in elevation 10 and partly broken away, of a shaving machine, showing a shaving knife in accordance with my invention in operative position;

Figure 2 is a fragmentary enlarged end view of the shaving knife and chip chute as seen out- 15 wardly in a radial direction from therecord;

Figure 3 is a side view of the shaving knife with the plane of its blade standing at an angle to the longitudinal axis of the record, showing means for adjusting the position of the knife to the record, and including a portion of the record, and

Figure 4 is a fragmentary view of the knife bar showing the knife holder and blade.

In order to clearly describe my invention, I show in Figure 1 a form of shaving machine in which my invention is preferably employed, which machine I now describe in detail as having mandrel I rotatably mounted on frame B and carrying phonograph record A for rotation in the direction of arrow C. A carriage 2 is supported slidably at its front end by a straight edge (not shown), and is mounted slidably and tiltably on a back rod 3, the latter being supported by spaced standards, one of which is shown at 4. The carriage 2 has an arm 5 carrying a feed nut 6 which, when the carriage 2 is in normal low- 'ered position, as shown, engages a feed screw 1 rotatably held in spaced standards, one of which is shown at I. Suitable gearing (not shown) 40 couples feed screw 1 to mandrel I. As mandrel I rotates, feed screw I is therefore made to rotate to eifect thereby a movement of the carriage 2 longitudinally with respect to the mandrel I.

The carriage 2 has an integral extension 2' 145 having an opening 8' through which extends a knife bar 8, this bar being mounted slidably for movement in a direction substantially radial to the mandrel I. Rotation of the knife bar 8 is prevented by an extension ll of bracket Il" engaging the longitudinal slot 8" of the knife bar. Knife bar 8 hasan outer end portion I6 of reduced diameter which extends loosely through the top end wall ll of a hollow cap I8, and has at its outer end a screw 2| which limits the outward movement of the cap I8. About the knife bar 8 between a collar 28 adjustably mounted thereon and the end wall I? of cap I8 is disposed a strong coil spring I9. Outward movement of the knife bar 8 is limited by the engagement of a collar 22 with the inner end mounting 2, the collar 22 being secured to knife bar 8 by means of a set screw 23. Attached rigidly to top wall II of cap I8 by a screw 25 is a guide rod 24, this rod being slidably mounted in an open ing 24' in the extension 2 of carriage 2. Between the outer end of mounting 2 and the end wall II of cap I8 is disposed a coiled spring 26 about the guide rod 24.

At the inner end of knife bar 8 is a knife bar extension I4 held rotatably thereto to permit an adjustment of knife bar extension I4 about the longitudinal axis of knife bar 8, this adjustment being secured by set screw I5. Knife holder 9 is held to extension I4 by pivot II! for turning movement thereabout, the axis of this pivot being normal to the longitudinal axis of knife bar 8. In the outer end of knife holder 9 is fixedly mounted knife blade II of hard material (preferably of sapphire) with this blade my invention is especially concerned, wherefore the blade is hereinafter described in detail.

In order that the cutting edge 3I of knife blade I I may engage record A most adaptly, knife blade II is movable about pivot I!) by adjustment of a screw I2, this screw having a large diameter portion with a coarse thread or worm which meshes with teeth on the inner end of knife holder 9, and having on a smaller diameter portion a fine thread which is in threaded engagement with the collar 22 as shown in cross section in Figure 3. The angle between the plane of knife blade I I and the longitudinal axis of record A is controlled, for example, by the adjustment of knife bar extension I4 about the axis of its connection to knife bar 8, which connection is made secure by the adjustment of set screw I5. In Figure 2 the plane of the knife blade is represented by the line FF and the longitudinal axis of the record by the line EE'. The angle between the plane of the knife blade H and the longitudinal axis of record A is represented by reference character 9.

In the resurfacing operation, cylindrical record A is placed on mandrel I for rotation about its longitudinal axis. Knife blade II is then adjusted in operative position against record A by manually depressing cap I8 until this cap contacts a stop 27, thereby resiliently pressing knife blade I I against record A through the resilient coupling of spring I9 between cap I8 and knife bar 8. In this position of knife bar 8 screw 28 is adjusted to force a clamping member 29, which is held in a slot 29' of member 2', against knife bar 8, thereby holding it in its adjusted operative position. As record A rotates its outer surface contacts shaving blade I I which is fed longitudinally along the record by carriage 2. The knife engages the record and cuts away a layer of the record material of a predetermined thickness. Record material thus cut away is referred to as shaving chips. These chips are thrown out into a chute I3, held to collar 22 by screws 30, which directs them downwardly and away from the record A. To facilitate the removal of the shaving chips the plane of the knife blade is always set at an angle to the longitudinal axis of the record. The chips are more readily thrown off as this angle is increased, except for such large angles as would place the plane of the blade in nearly normal relation to the longitudinal axis of the record.

Due to physical limitations, it is impossible to obtain a perfectly smooth surface in shaving cylindrical records. Some unevenness must be tolerated, but it is highly desirable that this unevenness be of the character of undulations of small curvature so as to avoid abrupt changes in surface levels. As a means for avoiding abrupt curvatures in the surface irregularities it has been customary practice to employ a shaving blade having a convexly shaped cutting edge. In feeding the convexly shaped knife blade along the surface of the rotating cylinder a groove is cut that progresses spirally about the cylinder. The curvature of the groove depends upon the effective cutting curvature of the blade-which effective cutting curvature depends upon the curvature of the cutting edge of the blade and the angle 9 between the plane of the blade and the longitudinal axis of the record. For easy chip removal this angle 6 is in practice at least 30 or more, under which condition the effective cutting curvature of the blade is considerably greater than the curvature of the blade itself. Stated differently, the inclined blade cuts a narrower groove, for a given depth of out, than would be cut with a blade parallel with the record longitudinal axis.

If the feed of the carriage, I or longitudinal movement per revolution of the cylindrical record, is small relative to the effective cutting width of the blade, the spiral groove overlaps so that in cutting each adjacent succeeding groove convolution a portion of the wall of each adjacent previous groove convolution is cut away. As the feed is made slower, more of this wall is cut away by what is in effect a compression of the spiral groove about the cylinder. This results in a smoother cut by reason of the ridges between the grooves being reduced in magnitude; but the shaving operation is made slower. This is objectionable and would be contrary to established principles in the art of shaving cylindrical phonograph records. Attempts to compensate for this slowness by increasing the rotating speed of the mandrel encounter practical limitations in the way of increased wear, suitable gearing ratios, vibratory effects and other attendant difficulties. If, however, a wide groove is cut of small curvature (large radius of curvature) there is a greater overlapping of adjacent groove convolutions in the shaving operation with a resultant improved smoothness of the surface. Moreover, with means for cutting a wide groove faster feeds may be employed to reduce the time required to perform the shaving operation. To secure these benefits, and other attendant advantages set forth in this specification, I employ in my invention a knife blade II having a concavely shaped cutting edge 3I. This edge may, for example, be that created between end face 33 and forward side 32 of blade I I, the forward side being that side of blade I I which first encounters the record A as the blade II is fed along the record surface.

In my invention, the radius of curvature of the cutting edge 3! is always greater than the radius of curvature of the record A being shaved, but I find it desirable in practice to have the former radius of curvature of the order of two to three times the latter-it being understood, however, that I intend no limitation to my invention in this respect. If the radius of curvature of the cutting edge 3I is very large, this edge will conform to the record surface throughout its length for a small value of the angle 9 between the plane of the blade and the longitudinal axis of the record;

and as the radius of curvature of cutting. edge 3| approaches invalue that of the record A, this conformation of the edge 3| to the record surface occurs at an increasingly larger angle 9 between the plane of the blade and the longitudinal axis of the record. In this relative position of the blade to the record there will be cut a square-cornered flat-bottomed groove throughout an isolated convolution, which is an undesirable form of groove; but with slight increases in theangle 9 there may be cut. wide shallow grooves free from: squarecornered edges, or with larger increases in the angle 9' there.- maybe out deeper but narrower grooves likewise free from the objectionable square-cornered edges. Due tothe fact that with a conventional resurfacing tool; having the convexly shaped cutting'edge there is a non-conformity' of the knife edge tothe record even when the plane of the blade is parallel to the longitudinal axis of the record, it is obvious that I cut a wider groove of smaller curvature than. is obtained with such a conventional tool, which wider groovemakes possible a smoother recordisurface. Moreover, for a given depth and curvature of groove, the angle 9 is greater than is possible with the conventional tool, thereby facilitating the. removal of theshaving chips; Practically there is a minimum value of angle 9 which permits easy chip removal, this value being of the order-of'30. This minimum" angle" 9 and the maximum depth of out required therefore determine the relative difference in radii of curvature between the cutting edge 31 and the record surface A tobe employed.

In the use of my invention I preferably associate therewith means for adjusting the angle between the plane of the blade and the-longitudinal axis of the record, as, for example, may be done with the rotatable connection between knife bar 8 and knife bar extension I4, already described, in order to obtain. a. high degreeof control in the use of the blade to meet most adaptly varying operating conditions. There is, for instance, encountered. the adverse condition in which the wax-like material of the record being shaved becomes soft as when subjected to Warm temperature. In such operating conditions there is a tendency for the knife blade to smear wherever extremely'shallow cuts are made; i l/henever smearing occurs there are increased difiiculties in shaving chip removal. In such cases a wide shallow groove may be less advantageous than the narrower groove. The knife blade is adjusted for maximum performance under such varying operating conditions by the means provided for changing the angle of the plane of the blade to the longitudinal axis of the record. The width of the groove is controlled by this adjusting means, and a groove of given width is always out with the plane of the blade inclined at a greater angle to the longitudinal axis of the record than is practicable with conventional tools, facilitating thereby the removal of the shaving chips under these adverse conditions.

I have hereinbefore described the concave cutting edge 3! as engaging the record in a manner that involves substantially equal relative separations of the ends of the cutting edge from the record axis. I intend no limitation of my invention in this respect, since modified cutting actions may be produced by differentiating these relative separations as by the turning of knife holder 9 about pivot 3 through the operation of adjusting screw l2. For such modified cutting actions I adjust the knife blade H relative to the record so that 3 the forward end ll of the cutting edge has a greater separationfrom the record axis than the backward end H, the forward end: H of course being that which encounters the record first in the travel; of the blade Ilalong the record surface. I prefer, however, that this adjustment be limited so that. the backward end ll" 'of the cutting edge 31 does not contact the record before an intermediate part ofthe cutting edge 3! as the blade H is brought into engagement with the record; Insuch relative position of the cutting edge 3! to the record I out throughout an isolated convolution a groove having a square corner adjacent the backward end i l" of the cutting edge 31 with a bottom of small curvature adjacent this square corner, but it is obvious that nosquare corners remain due to the overlapping of the convolutions. As a result deepercuts may be made without loss in record smoothness.

I also find it very desirable in the use of the concave cutting edge to provide a construction whereby a burnishing action is obtained over the shaved record surface. To secure the desired burnishing action, I provide a bladeli having a cutting edge 3! formed by the front side 32 and end face 33, which end face has a'slight bevel over a portion 33' immediately adjacent the cutting edge 3| and a steeper bevel over its remaining portion 33 Upon the engagement of the knife blade H with the record, the record material will tend to give as the cutting edge 3i rides over it. Afterwards, the record material springs back directly behind the cutting edge of the blade so that the portion 33' of the end face having the slight bevel will partially contact the record to cause a rubbing or burnishing action thereon and impart an added smoothness to the record surface. 7

It will be understood that While I' have illus trated and describedmy invention in terms of a specific embodiment, I intend no unnecessary limitations by virtue of the details of such embodiment, but rather undertake to express the scope of my invention in the following claims.

I'claim: 4

1. In a phonograph record shaving machine including means for rotating a cylindrical record: a resurfacing tool comprising a knife blade having a cutting edge engaging the record, said cutting edge being concavely shaped as viewed radially from said record and means for effecting relative movement between the record and said resurfacing tool longitudinally 'of the record.

2. In a phonograph record shaving machine including means for rotating a cylindrical record: a resurfacing tool comprising a knife blade having a concave end face which forms with the forward side of said blade a concave cutting edge engaging the record, and means for moving the resurfacing tool longitudinally of the record.

3. In a phonograph record shaving machine including means for rotating a cylindrical record: a resurfacing tool comprising a knife blade having a concave end face which forms with the forward side of said blade a concave cutting edge engaging the record, the plane of said knife blade being at an angle relative to the longitudinal axis of said record; and means for moving the resurfacing tool longitudinally of the record.

4. In a phonograph record shaving machine including means for rotating a cylindrical record: a resurfacing tool comprising a knife blade having a cutting edge engaging the record, said cutting edge being concavely shaped as viewed radially from the record, and the plane of said knifeblade being in the radial direction of said record and at an angle to the longitudinal axis of said record; and means for moving the resurfacing tool longitudinally of the record.

5. In a phonograph record shaving machine including means for rotating a cylindrical record: a resurfacing tool comprising a knife blade having a concave end face which forms with the forward side of said blade a concave cutting edge engaging the record; said end face having a slight bevel immediately adjacent said cutting edge, and having a steeper bevel over its remaining portion.

6. In a phonograph record shaving machine including means for rotating a cylindrical record: a resurfacing tool comprising a knife blade having a concave end face which forms with the forward side of said blade a concave cutting edge engaging the record, the plane of said knife blade being at an angle relative to the longitudinal axis of said record, said end face having a slight bevel immediately adjacent said cutting edge, and having a steeper bevel over its remaining portion.

'7. In a phonograph record shaving machine including means for rotating a cylindrical record: a resurfacing tool comprising a knife blade having a concave end face which forms with the forward side of said blade a concave cutting edge engaging the record; and means for adjusting the angle of the plane of said knife blade relative to the longitudinal axis of said record.

8. In a phonograph record shaving machine including means for rotating a cylindrical record: a resurfacing tool comprising a knife blade having a concave end face which forms with the forward side of said blade a concave cutting edge engaging the record, said end face having a slight bevel immediately adjacent said cutting edge, and having a steeper bevel over its remaining portion; and means for adjusting the angle of the plane of said knife blade relative to the longitudinal axis of said record.

9. In a phonograph record shaving machine including means for rotating a cylindrical record: a resurfacing tool comprising a knife blade having a concave cutting edge viewed radially from the record, the plane of said knife blade being in the radial direction of said record; and means for adjusting the angle of the plane of said blade relative to the longitudinal axis of said record.

10. In a phonograph record shaving machine: the combination, with a cylindrical record and means for rotating the same, of a knife blade having a concave cutting edge engaging the record; and means for moving the knife blade along the record.

11. In a phonograph record shaving machine: the combination, with a cylindrical record and means for rotating the same, of a knife blade having a concave cutting edge engaging the record, and means for adjusting the angle of said blade relative to the longitudinal axis of said record.

12. In a phonograph record shaving machine including means for rotating a cylindrical recrd: a resurfacing tool comprising a knife blade having a concave end face which forms with the forward side of said blade a concave cutting edge engaging the record, the ends of said cutting edge being of unequal distance from the axis of said record.

13. In a phonograph record shaving machine including means for rotating a record: a resurfacing tool comprising a knife blade having a concave end face'which forms with the forward side of said blade a concave cutting edge engaging the record; and means for controlling the relative separations of the ends of the cutting edge from the axis of said record.

14. In a phonograph record shaving machine including means for rotating a record: a resurfacing tool comprising a knife blade having a concave end face which forms with the forward side of said blade a concave cutting edge engaging the record; means for adjusting the angle of the plane of said knife blade relative to the axis of said record, and means for controlling the relative separations of the ends of the cutting edge from the axis of said record.

15. In a phonograph record shaving machine including means for rotating a record: a resurfacing tool comprising a knife blade having a concave end face which forms with the forward side of said blade a concave cutting edge engaging the record, said end face having a slight bevel immediately adjacent said cutting edge, and having a steeper bevel over its remaining portion; and means for controlling the relative separations of the ends of the cutting edge from the axis of said record.

WALTER H. MILLER. 

